Can't get off the ground
10-10-2008, 01:38 PM
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Can't get off the ground
Hi Everyone,
I have been flying nitro for a few years now and with the recent price of the fuel I decided to try electric. I bought a HK outrunner and esc combo from ebay it is listed as
1 x MYSTERY 80A Speed Controller ESC
1 x BEC 3A 5-6V
1 x RC 480KV Outrunner Brushless Motor
I have a 11.1 3sp1 lipo 2650 mah 25C battery for powering it up.
I have a 10X7E apc prop.
I have a medium sized upper wing foam plane scratch built 30" length wing is 40" x 8" the whole plane is just over 2.3 lbs with flight gear and battery installed.
The problem is that it don't seem to have enough power to get it off the ground and a hand launch had the same result right back down it came under full power and up elevator.
I am going to try a bigger prop to start. Has anyone tried these HK motore from ebay? they look well built. I thought I had it figure at 726 watts which should be way more than enough from what I read. I am looking for any help that I can get to figure this out.
Thank You
Hitster4
I have been flying nitro for a few years now and with the recent price of the fuel I decided to try electric. I bought a HK outrunner and esc combo from ebay it is listed as
1 x MYSTERY 80A Speed Controller ESC
1 x BEC 3A 5-6V
1 x RC 480KV Outrunner Brushless Motor
I have a 11.1 3sp1 lipo 2650 mah 25C battery for powering it up.
I have a 10X7E apc prop.
I have a medium sized upper wing foam plane scratch built 30" length wing is 40" x 8" the whole plane is just over 2.3 lbs with flight gear and battery installed.
The problem is that it don't seem to have enough power to get it off the ground and a hand launch had the same result right back down it came under full power and up elevator.
I am going to try a bigger prop to start. Has anyone tried these HK motore from ebay? they look well built. I thought I had it figure at 726 watts which should be way more than enough from what I read. I am looking for any help that I can get to figure this out.
Thank You
Hitster4
10-10-2008, 02:09 PM
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RE: Can't get off the ground
My first guess is that with such a low KV motor you need a much larger prop both in pitch and diameter. I suspect you should also go to a 4S LiPo. Without more specifics on both the motor and the ESC it's hard to be sure.
Walt
Walt
10-10-2008, 02:47 PM
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RE: Can't get off the ground
Yep, or you need to really step up the cell count.
Did some playing on MotoCalc. your set us is showing roughly only 6.6 amp draw, 13.4 oz of thrust and a prop speed of 33.5 mph
Bump the same set up to 6 cells and reads are like this, 17.2 amps, 49.2 thrust, 64.1 prop speed.
If you had two of the 3 cell packs, you could series wire them together, this would let you see how it performs, just watch your flight time, as 17 amps from a 2100 pack won't be real long.
Did some playing on MotoCalc. your set us is showing roughly only 6.6 amp draw, 13.4 oz of thrust and a prop speed of 33.5 mph
Bump the same set up to 6 cells and reads are like this, 17.2 amps, 49.2 thrust, 64.1 prop speed.
If you had two of the 3 cell packs, you could series wire them together, this would let you see how it performs, just watch your flight time, as 17 amps from a 2100 pack won't be real long.
10-10-2008, 03:20 PM
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RE: Can't get off the ground
That was my thought moving to a 6s2p and changing the prop to a 13X10e the flight times will be short but will add better battery this is for training a few friends how to fly and me on what to use to get it to fly.
Thanks again
Hitster4
Thanks again
Hitster4
10-10-2008, 04:21 PM
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RE: Can't get off the ground
actually a 6S2P 2100 mah pack will get you 4200 mah and should give really nice flight times especially at only 17 amps. I think the 13/10e prop sounds about right as does the 6S (which is what gives you more voltage. The "2P" gives you more duration and the potential for higher amp draw).
Walt
Walt
